Move stroke preview render mapping to renderer gl

docs/modernization/roadmap.md

@@ -456,6 +456,9 @@ formats to `pp_renderer_gl`.
 Legacy `util.cpp` OpenGL error naming and `gl_state` save/restore now delegate
 error codes, state queries, framebuffer targets, texture binding targets, and
 active texture units to `pp_renderer_gl`.
+`NodeStrokePreview` brush preview rendering now delegates depth/scissor/blend
+state, viewport/clear-color queries, active texture units, 2D texture targets,
+copy targets, and sampler filters/wraps to `pp_renderer_gl`.
 The existing renderer classes are not yet fully
 behind the renderer interfaces.